To improve low temperature flexibility of transparent thermoplastic polyurethane (referred as “TPU” hereinafter) resin, the resin composition composed of TPU resin and graft rubber has been studied for a long while.
U.S. Pat. No. 3,049,505 (granted on Aug. 14, 1962) and U.S. Pat. No. 4,317,890 (granted on Mar. 2, 1982) describe a TPU resin composition composed of ABS (acrylonitrile-butadiene-styrene) graft copolymer and TPU resin. However, the problem of these inventions is the final resin composition becomes opaque owing to the difference of refraction index between the two major components.
Therefore, it is urgently requested to develop a novel TPU resin composition with improved transparency and low temperature impact strength as well.